(a) Field of the Invention
The present invention relates to a direct motor-drive portable angle grinder with a disc type motor installed in a position adjacent to the grinding wheel and an outer motor rotating part coaxially and directly driving the grinding wheel. By means of the direct drive, the present invention prevents the emission of noise made by angle type transmission devices. Moreover, an inertial body is installed on the rotating housing that is integrated with the rotating part to form a flywheel or the rotating housing and the inertial body are integrated into a single reinforced structure to enable a flywheel function in order to improve the grinding, polishing and machining or cutting abilities of the grinding wheel. Aside from a manually controlled electromechanical device, a power storing and discharging device is also installed in the handle for use as a power source.
(b) Description of the Prior Art
Traditional motor-driven right-angle type portable grinder is an electrical tool designed according to ergonomics. Its structural features are the following:
(1) The angular difference between the handle axis extending from the housing and the grinding wheel axis is between 30° and 150°;
(2) The electric motor is installed in the handle;
(3) An angle type transmission device such as a bevel gear set is present in between the grinding wheel spindle and the handle motor spindle;
Because the above structure necessitates an angle type transmission device; hence its deficiency is its very loud noise.